Heart valve prostheses

ABSTRACT

A prosthetic heart valve includes a prosthetic valve annulus and at least one prosthetic valve leaflet member including at least one coaptation surface configured for cooperating with at least one corresponding coaptation surface of the prosthetic heart valve. At least one valve leaflet member is displaceable by blood flow between a closed position and an open position to produce, correspondingly, a contact and a separation of cooperating coaptation surfaces. In the open position the separation of the cooperating coaptation surfaces enables the blood flow through the orifice in a first direction, and in the closed position the contact of the cooperating coaptation surfaces prevents the blood flow through the orifice in a second direction, opposite to the first direction. The prosthetic heart valve includes at least one device configured for preventing at least in part the contact between cooperating coaptation surfaces, so that a blood regurgitation in the second direction is enabled, wherein the at least one device is configured for ceasing its action after a predetermined amount of time.

FIELD OF THE INVENTION

The present description refers to heart valve prostheses, both of thebiological and of the mechanical type including a prosthetic valveannulus defining an orifice for the passage of blood flow and at leastone prosthetic valve leaflet member configured for regulating the bloodflow through said prosthetic valve annulus.

BACKGROUND

Cardiac valve insufficiency is a pathology that generally leads to asurgical intervention for the replacement of the diseased native heartvalve. In the field of heart valve surgery both biological andmechanical prostheses are known, the former being generally made fromportions of biological tissue (for example bovine pericardium), thelatter being made e.g. either of metal materials, polymeric materials orcomposite materials, possibly clad with a biocompatible coating (i.e.pyrolitic carbon).

In a large majority of cases, a diseased native heart valve is found toallow a blood regurgitation through the leaflets, whereby a fraction ofthe blood flow which is actively (i.e. by a positive action) displacedby the pulsating heart leaks through the diseased valve in a directionopposite to that normally intended for the passage of blood flow due tosub-optimal coaptation of the valve leaflets.

Taking a diseased native heart valve as example, it is known that whenthe mitral valve is regurgitating a progressive decrease in leftventricle afterload (due to low pressure backward blood flow) and volumeoverload (i.e. high preload due to the regurgitated blood volume)occurs. This results, i.a. in a variation of the enzymatic myocytesequipment and of the pattern of actine-myosine cross bridge.

In other words, the entire heart cycle is affected, because the leftventricle experiences a lower blood pressure when ejecting blood throughthe aortic valve during systole due to the blood leak through thediseased mitral valve.

Additionally, when admitting blood into the left ventricle (diastole)via the mitral valve from the pulmonary veins, the left ventricleexperiences a higher than normal preload due to the additional volume ofblood that had previously leaked through the diseased valve due to theregurgitation and that now flows back in.

When a diseased mitral valve is replaced, the left ventricle experiencesa sudden increase in afterload and a simultaneous decrease in preload.The first effect is due to the replacement mitral valve (i.e.prosthetic) being designed not to allow any blood leak (regurgitation)therethrough, so that when ejecting blood through the aortic valveduring systole, the left ventricle experiences a higher blood pressurethan that experienced with the diseased mitral heart valve because noblood leak occurs through the prosthetic mitral valve.

The second effect is due to the substantial absence of the regurgitatedblood volume in the left ventricle during diastole.

A preload/afterload mismatch therefore occurs, which may lead to a leftventricle failure. Additionally, myocardial oxygen needs may increase asa consequence of a higher energy demand.

This furthermore may result in an intractable cardiogenic shock. In thissituation the recovery sometimes requires several days of inotropicsupport.

OBJECT AND SUMMARY

It is therefore an object of the invention that of improving thepost-operative recovery after a valve replacement surgical intervention.

The above object is achieved by a prosthetic heart valve having thefeatures of one or more of the claims that follow. The claims form anintegral part of the technical disclosure herein provided in relation tothe invention.

More particularly, the object is achieved by a prosthetic heart valveincluding:

-   -   a prosthetic valve annulus defining an orifice for the passage        of blood flow,    -   at least one prosthetic valve leaflet member including at least        one coaptation surface configured for cooperating with at least        one corresponding coaptation surface of said prosthetic heart        valve to regulate blood flow through said orifice, said at least        one valve leaflet member being displaceable by the blood flow        between a closed position and an open position to produce,        correspondingly, a contact and a separation of cooperating        coaptation surfaces,

wherein in the open position the separation of the cooperatingcoaptation surfaces enables the blood flow through said orifice in afirst direction, and

wherein in the closed position the contact of the cooperating coaptationsurfaces prevents the blood flow through said orifice in a seconddirection, opposite to said first direction,

wherein the prosthetic heart valve includes at least one deviceconfigured for preventing at least in part the contact betweencooperating coaptation surfaces, so that a blood regurgitation in saidsecond direction is enabled, and wherein said at least one device isconfigured for ceasing its action after a predetermined amount of time.

BRIEF DESCRIPTION OF THE FIGURES

Various embodiments of the invention will now be described withreference to the attached figures, provided purely by way of nonlimiting example, and wherein:

FIG. 1 is a sectional, schematic, view of heart valve prosthesisaccording to various embodiments in a first operating condition,

FIG. 2 is a view according to the arrow II of FIG. 1,

FIG. 3 is a sectional, schematic, view corresponding to that of FIG. 1but showing the valve prosthesis in a second operating configuration,

FIG. 4 is a view according to arrow IV of FIG. 3,

FIG. 5 is a partly sectioned, schematic, view of a detail indicated bythe arrow V in FIG. 1,

FIG. 6 is a sectional view according to the line VI-VI of FIG. 5 andshowing a first condition,

FIG. 6A is an enlarged sectional view of FIG. 6,

FIG. 6B is a partial view according to the arrow VI/B of FIG. 6A,

FIG. 6C is a partial view of a detail of FIG. 6A, sectioned along theline VI/C-VI/C of FIG. 6A

FIG. 7 is a sectional view corresponding to that of FIG. 6 and showinganother condition,

FIG. 8 is a partly sectioned, schematic, view corresponding to that ofFIG. 5 but according to further embodiments of the invention,

FIG. 9 is a sectional view according to the line IX-IX of FIG. 8,

FIG. 10 is a schematic view of detail according to the arrow X of FIG.1,

FIG. 11 is a sectional, schematic, view according to the line XI-XI ofFIG. 10,

FIG. 12 is a perspective, schematic, view of a prosthetic heart valveaccording to further embodiments of the invention,

FIGS. 13 and 14 are views according to the arrow XIII of FIG. 12 andshowing two different operating conditions,

FIG. 15 illustrate a heart valve prosthesis according to furtherembodiments, and

FIG. 16 illustrates a heart valve prosthesis according to yet furtherembodiments.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following description, numerous specific details are given toprovide a thorough understanding of embodiments. The embodiments can bepracticed without one or more of the specific details, or with othermethods, components, materials, etc. In other instances, well-knownstructures, materials, or operations are not shown or described indetail to avoid obscuring aspects of the embodiments.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, the appearances of the phrases “in oneembodiment” or “in an embodiment” in various places throughout thisspecification are not necessarily all referring to the same embodiment.

Furthermore, the particular features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments.

The headings provided herein are for convenience only and do notinterpret the scope or meaning of the embodiments.

In FIGS. 1 and 3 the reference number 1 identifies as a whole a heartvalve prosthesis according to various embodiments and of the mechanicaltype.

The heart valve prosthesis 1 includes a prosthetic valve annulus 2 whichin various embodiments may be a ring member having a wall thickness tand to which at least one prosthetic valve leaflet member 4 is movablyconnected. By the term “movably connected” it is meant to indicate thepresence of a coupling that allows a movement of the leaflet along atleast one degree of freedom to simulate the behaviour of a native valveleaflet. Furthermore, the term “leaflet member” as used herein isintended to cover any device or component that is capable of providingan action aimed at reproducing that of a native valve leaflet.

Examples of such components/devices may include “mechanical” prostheticvalve leaflets (i.e. intended to be applied on mechanical heart valveprostheses), “biological” prosthetic valve leaflets (i.e. made ofbiological tissue) and also ball members of mechanical “ball valve”prostheses, which are capable of regulating the blood flow as well asany other previously mentioned device.

For this reason, and for the sake of conciseness, the generic term“leaflet” will be primarily used herein, such term being intended toencompass, where applicable, one or more of the devices/componentsmentioned above.

In various embodiments the at least one prosthetic valve leafletincludes at least one coaptation surface configured for cooperating withat least one corresponding coaptation surface of the prosthetic heartvalve to regulate blood flow through the orifice defined by theprosthetic valve annulus 2. In some embodiments, a first coaptationsurface may be provided on the edge of the leaflet 4 and a secondcoaptation surface may be provided by the prosthetic valve annulus 2itself (for example in tilting disc prosthetic heart valves).

In other embodiments, such as those shown in FIGS. 1 to 4, theprosthetic heart valve 1 includes two leaflets 4 pivotable aroundrespective axes X1, X2 (orthogonal to a main axis Z1 of the heart valveprosthesis and of the prosthetic valve annulus 2), generally D-shapedand each including first coaptation surfaces C1, C2, C3, C4 which areconfigured for cooperating with corresponding second coaptation surfacesC5, C6 provided on the valve annulus 2, as well as with a correspondingcoaptation surface C1 of the other leaflet 4 (see below for details).

In particular, in various embodiments:

the coaptation surface C1 is provided in correspondence of a straightportion of the “D” shape of each leaflet and it is configured forcooperating with the corresponding coaptation surface C1 on the othervalve leaflet;

the coaptation surface C2 is provided at the curved portion of the “D”shape and it is configured for cooperating with a correspondingcoaptation surface C5 on the inner surface of the prosthetic valveannulus 2,

the coaptation surfaces C3, C4 are provided at parallel rectilinearportions of the “D” shape orthogonal to the straight portion whereat thesurface C1 is provided, and are located on opposite sides with respectto the surface C1; the coaptation surfaces C3, C4 are configured forcooperating with corresponding coaptation surfaces C6 on the prostheticvalve annulus 2.

Generally, it may be said that in various embodiments each leafletincludes at least one coaptation surface which is adapted to cooperatewith another coaptation surface which is provided on the valve, thismeaning that the second coaptation surface may be located either onanother leaflet or on the prosthetic valve annulus or both.

In various embodiments, the prosthetic heart valve 1 includes one ormore devices configured for influencing the contact between thecooperating coaptation surfaces when the leaflets are displaced towardsa closed position.

With specific reference to FIGS. 1 to 4, a schematic representation oftwo such devices is indicated respectively with reference numbers 8, 10.Note that in the figures shown herein both the devices 8, 10 aredepicted, but in various embodiments it is envisaged that only one ofthe devices 8 or 10 be provided. Furthermore, in the examples shown inthe figures, the devices 8, 10 are provided in pairs, namely there is atleast one device 8, 10 operatively associated to each leaflet 4, butembodiments are also possible wherein one and only device 8, 10 isprovided and operatively associated to one leaflet only.

However, in some embodiments both the devices 8, 10 may be present.

In various embodiments, the device 8 is a peripheral device, configuredfor exerting its action at the prosthetic valve annulus, while thedevice 10 is a leaflet device, i.e. configured for exerting its actionat the prosthetic valve leaflets.

Generally, the action of such devices 8,10 is aimed at preventing thecomplete closure of the heart valve prosthesis so to allow a temporaryregurgitation of blood through the valve prosthesis itself. Furthermore,as will be detailed in the following, such devices are configured forceasing their action after a predetermined amount of time in order torestore the full performances of the heart valve prosthesis.

In various embodiments, each device 8, 10 is configured for preventingat least in part the contact between cooperating coaptation surfaces, soto enable a blood regurgitation through the prosthesis 1.

In the embodiments depicted in FIGS. 1 to 4, the peripheral device 8 maybe located on the surface C5 (i.e. on the valve annulus 2) and it isconfigured for contacting the valve leaflet 4 in order to avoid thecontact between the coaptation surfaces C2, C5 at at least a portion ofthe respective contact areas. In other embodiments it may be envisagedto have the device 8 applied to the valve leaflet 4 (i.e. applied to thecoaptation surface C2). Note that the at least partial lack of contactcreated between the surfaces C5 and C2 also leads to the lack of contact(at least in part) of other cooperating coaptation surfaces, namely thesurfaces C1 on the edge of the leaflets 4 and the surfaces C3, C4 andC6.

In such embodiments it is preferable that the device 8 be sized anddimensioned so to prevent at least in part the contact between a pair ofcooperating coaptation surfaces without contacting directly thecoaptation surface on which it is not applied.

This in order to prevent the leaflets from being locked in the closedposition. In fact, it is not unlikely that in case the device 8 were tocontact both the cooperating coaptation surfaces, the device 8 would—inthe closed position of the leaflets 4—be “squeezed” between the leaflet4 itself and the annulus 2, thereby creating an interference fit of theformer into the latter. This mainly because the closure forces acting onthe valve leaflets are typically higher than the opening forces.

The second device 10 may be positioned at the coaptation surface C1 ofeach valve leaflet.

In various embodiments, each device 8, 10 may be in the form of a web, awedge, a tab, a patch, a relief, a shim or a film, or any possibleequivalent.

In one embodiment, including only two peripheral devices 8, each device8 is a 0.6 mm thick patches. In another embodiment, including only twoleaflet devices 10 (each associated to a respective prosthetic valveleaflet 4), each device 10 is a 0.2 mm thick patch or film. In bothcases, a regurgitation area of approximately 25 mm² can be obtained.

As previously set forth, each device 8, 10 is configured for allowing atemporary blood regurgitation through the prosthetic heart valve 1.Further details are provided below.

As well known, the prosthetic valve leaflets 4 are displaceable by theblood flow between a closed position (shown in FIGS. 3 and 4) and anopen position (shown in FIGS. 1 and 2) to produce, correspondingly, acontact and a separation of the cooperating coaptation surfaces.

In the open position of the prosthetic valve leaflets (this appliesregardless of the number of the valve leaflets, i.e. when there is onlyone valve leaflet or more than two) the separation of the cooperatingcoaptation surfaces (in these embodiments C1, C2, C3, C4, C5, C6—seeabove for details about the coaptation—) enables the blood flow throughthe orifice in a first direction F1.

In the closed position the contact of the prosthetic valve leaflets 4the contact of the cooperating coaptation surfaces (in these embodimentsC1, C2, C3, C4, C5, C6—see above for details about the coaptation—)prevents the blood flow through the orifice in a second direction F2,opposite to the first direction F1.

In various embodiments, each device 8, 10 is configured for preventingat least in part the contact between the first and second cooperatingcoaptation in order to prevent a complete closure of the valveleaflet(s) and enable thereby a blood regurgitation in the seconddirection F2.

Furthermore, in various embodiments the devices 8, 10 are made at leastin part of bio-degradable and/or bio-resorbable material, i.e. amaterial which is capable of disappearing after a pre-determined amountof time, for example due to the erosion action conveyed by the bloodflow. In this way, the action of the devices 8, 10 may cease after sucha pre-determined amount of time.

Examples of bio-degradable/bio-resorbable materials which may be usedfor the devices 8, 10 may include bio-resorbable polymer gels such as3-hydroxypropionic acid, polylactic (L, DL) acid, poly caprolactone,poly glycolide, poly lactic co-glycolide, poly dioxanone, polytrimethylcarbonate, ε-polylysine, hyaluronic acid, poly saccharides.Additionally, bioresorbable magnesium alloys may also be used, forexample in embodiments such as those shown in FIGS. 10-11.

In various embodiments the bio-degradable/bio-resorbable material may bechosen so to exhibit a full degradation in 3 to 6 weeks for example bysurface or bulk erosion, or even by poor elasticity.

Generally it is preferable that the bio-degradable/bio-resorbablematerial have a sufficient diffusion in the blood flow, and thediffusing area and diffusibility of the bio-degradable/bio-resorbablematerial are chosen accordingly.

In other embodiments, the bio-degradable/bio-resorbable material may bechosen among gels which exhibit a full degradation in 3-6 weeks bysurface erosion only. Preferably the gel should exhibit high resistanceto pressure, small elasticity and high adhesivity on carbon, in order toachieve a sufficiently strong connection with a bio-compatible coatingpossibly applied to the prosthetic heart valve 1.

In other embodiments, a polymer gel which exhibits full degradation in 3to 5 weeks by surface erosion only may be chosen, and preferably a gelexhibiting high adhesivity on tissues is chosen.

Thanks to the presence of the devices 8 or 10 the alteration of thepreload and the afterload of the left ventricle, in case the prostheticvalve 1 is used for mitral valve repair, may be consistently reduced.

In particular, after diastole—wherein a blood flow to the left ventricleis enabled by the valve leaflets 4 in the open position as shown inFIGS. 3, 4—the complete closure of the valve leaflets 4 is prevented bythe devices 8, 10.

Note in this respect the outline of each valve leaflet 4 in dashed linewhich provides evidence of the position of the regurgitation area RAresulting from the lack of contact in correspondence of at least aportion of the coaptation surfaces at (and near) the location of thedevices 8, 10.

In this way, still with reference to a mitral valve repair, duringsystole a blood back flow to the left atrium is enabled through theregurgitation area RA so that the behaviour of the newly implanted heartvalve prosthesis 1 resembles that of the diseased native heart valve.

In the diastole that follows the regurgitated blood volume enters theleft ventricle, thereby resembling the behaviour of the diseased nativeheart valve. So to say, thanks to the prosthetic heart valve 1 accordingto the embodiments herein described, the heart perceives only slightchanges with the respect to the operation with the diseased native heartvalve, which helps in minimizing the negative impact of the valve repairintervention on the patient.

As time passes by the volume of the devices 8 or 10 is progressivelyreduced due to erosion and/or degradation caused, for example, by theblood flow which impinges thereupon.

This gradually leads to the increase of the contact area betweencooperating first and second coaptation surfaces, thereby reducing as aconsequence the regurgitation area RA.

In this way the pre-load (i.e. the end-diastolic volume) is graduallydecreased to normal values while the afterload is gradually increasedbecause the blood leaks through the regurgitation area RA during systoleget progressively smaller.

When the devices 8 or 10 have been eroded to such an extent that theycease their action (either because they are completely disappeared, or,as will be described in the following, because a positional andvolumetric variation occurred) the full contact area between thecooperating coaptation surfaces of the valve leaflets and the prostheticvalve annulus 2, 4 is restored, thereby enabling the prosthetic heartvalve 1 to function according to design specifications.

With reference to FIGS. 5 to 7, further embodiments of the device 8 areshown in enlarged views. In such embodiments, the device 8 may take theform of a hollow cylindrical sector housed in a local enlargement 20 ofthe wall thickness t of the prosthetic valve annulus 2, wherein theenlargement 20 preferably protrudes in radial direction outwards of theannulus 2 for the passage of blood flow. In some embodiments the localenlargement may be 1.8 mm (including the wall thickness t, which invarious embodiments is equal to 1 mm).

In various embodiments the device 8 may include a first portion 80 madeof substantially rigid, non bioresorbable/non-biodegradable materialwhich is into contact with (in some embodiments attached to) a secondportion 81 which in various embodiments is made of abio-resorbable/biodegradable material, e.g. a bioresorbable gel or abioresorbable polymer. In other embodiments, the biodegradable materialused for the portion 81 may be more rigid than a polymer gel (e.g. abioresorbable magnesium alloy can be used) so that it can offer a higherresistance to external action but anyway the portion 81 shall be made ofbiodegradable material.

Within the local enlargement 20 there may be provided guide walls 82which are configured for guiding the portion 80 in a sliding movementtherethrough.

Thanks to the presence of the guide walls 82 the portion 80 can thusslide inwards and (theoretically) outwards of the prosthetic valveannulus 2, in a way which will be described in the following.

Guide walls 82 define a cavity 820 which in various embodiments isfilled partly by the portion 81

In various embodiments The first portion 80 is in part housed within thecavity 820 in the volume not occupied by the portion 81, and in part(preferably a larger part) it protrudes out of the cavity defined by theguide walls 82 and inwards of the orifice for the passage of blood flow,as shown in FIG. 6.

This corresponds to the condition (shown in FIG. 6) of the device 8 on anew, ready to be implanted prosthetic heart valve (and even a newlyimplanted one, in the very first stint of its service life). In otherwords, when the second portion 81 has a maximum volume (corresponding tothe beginning of service life), the first portion 80 of the hollowcylindrical sector protrudes outwards of the cavity 820 and radiallyinwards of the orifice of the heart valve prosthesis 1 by a maximumextent, so that the regurgitation area created thereby is also at amaximum value.

In this condition, at least a leading edge 800 of the portion 80contacts a surface of the valve leaflet 4, thereby preventing at leastin part the contact of the coaptation surfaces C2, C5. The contactbetween other cooperating coaptation surfaces (e.g. C3, C4 and C6) willbe accordingly affected, taking into consideration the geometry of thevalve leaflet 4.

In various embodiments, the portion 80 may be biased inwards into thecavity 820 and against the portion 81 by an elastic biasing element 83which may take the form of a torsion wire or a helical spring wound witha small diameter. In various embodiments the elastic biasing element 83may be made of steel or titanium alloy or even a shape memory materialsuch as Nitinol.

In such embodiments, the elastic biasing element 83 may include a wirelike element helically wound and having a first end 84 which isconnected to the prosthetic valve annulus 2 and a second end 85 which isconnected to the portion 80.

In some embodiments, in order to facilitate the positioning of theelastic biasing element 83, a miniaturised pin 86 may be provided withinthe prosthetic valve annulus 2 at the local enlargement 20 so that itprovides both a position reference and a support to the elastic biasingelements 83.

In various embodiments only one elastic biasing element 83 is providedfor each device 8. In other embodiments, such as those shown in FIG. 5,a pair of elastic biasing elements 83 is arranged on opposite sides ofthe hollow cylindrical device 8.

After the implantation of the heart valve prosthesis, the blood flowthat impinges upon the heart valve prosthesis 1 and in particular on theprosthetic valve annulus 2 gradually erodes thebiodegradable/bioresorbable material of which the portion 81 is made.Blood may penetrate through the clearance between the portion 80 and theguide walls 82, so that it can reach the portion 81.

In greater detail, in one embodiment a biodegradable gel is chosen as abiodegradable/bioresorbable material. The biodegradable gel fills theempty space corresponding to the portion 81 and the clearance S betweenthe portion 80 and the guide walls 82 (see FIGS. 6A-6C), which prolongsthe portion 81.

The contact area (at which erosion occurs) between the blood stream andthe biodegradable gel corresponds—so to say—to a cross section of theclearance S, i.e. it has substantially the shape of a rectangular framesurrounding the portion 80.

When the recoil mechanism of the portion 80 (e.g. the elastic biasingelement 83) exerts its action on the portion 80 itself, pressure isapplied on the gel of the portion 81, so that any eroded volume of gelat the interface with the blood stream promotes a roll-in movement ofthe portion 80 resulting in an “extrusion” of the portion 81 of the samevolume through the clearance S.

At the same time, the action of the elastic biasing element 83 pushesthe portion 80 back into the cavity 820, and gradually reduces theextent by which the portion 80 protrudes radially inwards of theprosthetic valve annulus 2.

As the portion 80 is gradually rolled back into the cavity between thewalls 82, the coaptation surfaces C2, C5 get into contact with oneanother at a progressively larger area when the valve leaflets 4 arebrought in the closed position (the same goes, accordingly, with theother affected cooperating coaptation surfaces), and the regurgitationarea RA is reduced accordingly.

When the portion 80 is completely housed in the valve annulus 2, theresidual volume of gel is equal to that of the clearance “S” (i.e.contact area multiplied by extension of the clearance).

In this situation, the position of the portion 80 is maintained fixed bythe guide walls 82 (in particular that at the bottom of the cavity 820),so that any action possibly exerted by the elastic biasing element 83results in no displacement of the portion 80, therefore no furtherextrusion of the gel will occur. The residual volume of gel will betrapped in the clearance S and the area in contact with the blood flowwill clot and then will be filled by fibrosis.

FIG. 7 shows the condition of the device 8 after the portion 81 has beencompletely eroded by the blood flow. The portion 80 is completelyretracted inside the valve annulus 2, in particular inside the localenlargement 20, and it is held in position by the action of the elasticbiasing element 83.

Note that in various embodiments the angular extension of the portion 80of the device 8 is chosen so that, when the device 8 is completelyretracted inside the cavity 820, the leading surface thereof lies flushwith or slightly below the inner cylindrical wall of the prostheticvalve annulus 2. This in order not to impede the complete and optimalcontact between the coaptation surfaces C2, C5 and in order not todisturb the blood flow when the leaflets 4 are in the open position.

In some embodiments the final position (i.e. that shown in FIG. 7) ofthe portion 80 may be locked by the combined action of the biasingelement 83 and a pawl member (not shown) in order to ensure that noundesired displacement (rollout) of the portion 80 will occur.

With references to FIGS. 8, 9, a variant of the embodiments depicted inFIGS. 5 to 7 is shown in enlarged scale. The difference residesprimarily in the smaller dimensions of the peripheral device 8, becausein such embodiments the device 8 is housed completely within the wallthickness t of the annulus 2, without any local enlargement thereof.

The operation of the peripheral device 8 is exactly the same asdescribed with reference to FIGS. 5 to 7 and the reference numbers,where identical to those previously used, denote the same components.

In other embodiments, the torsion wire 83 may be substituted by aminiaturized, remotely controlled actuator configured for rolling theperipheral device 8 back into the cavity 820, so that the action of thedevice 8 may cease after a predetermined amount of time.

With reference to FIGS. 10, 11, an enlarged view of the second device(leaflet device) 10 is provided herein. In various embodiments theleaflet device 10 may take the form of a film ofbio-degradable/bio-resorbable material applied on a portion of thecoaptation surfaces C1 of the leaflets 4. In various embodiments, such afilm may extend over the entire area of the coaptation surfaces C1,while in other embodiments the film 10 may extend only for part of thelength (in the direction of the axes X1, X2) of the valve leaflets 4and/or only for part of the thickness of the valve leaflets 4.

Whatever form and extension the device 10 may be given, the actionthereof prevents at least in part the contact of coaptation surfaces C1of the valve leaflets 4 (i.e. at least a portion of the contact areathereof), so that a regurgitation area RA is created between theleaflets 4 (see FIG. 10). Of course, due to the geometry and thearrangement of the leaflets 4, the lack of contact between thecoaptation surfaces C1 also results in a lack of contact at one or morelocations of the cooperating coaptation surfaces C2, C5 and C3-C4, C6.

Generalizing, regardless of the provision of a peripheral or a leafletdevice 8, 10, a regurgitation area RA will be created both between theleaflets 4 and between the leaflets and the annulus 2.

In various embodiments, a contact occurs directly between the devices 10on each leaflet 4: in this case the risk of having the leaflets lockedin the closed position is quite lower than that affecting the peripheraldevices 8 because, due to the position of the axes X1, X2 (closer to themain axis Z1 of the valve prosthesis 1) the opening forces have a morefavourable lever ratio. To this end, it is however preferable that thebio-degradable/bio-resorbable material of the device 10 be chosen sothat separate pieces thereof (e.g. those of the two leaflet devices 10)do not exhibit reciprocal adhesion properties.

In further embodiments both the devices 8, 10 may be present and theymay be exploited for example in such manner.

The materials of each device may be chosen so to erode over differenttime spans. The device made of the material with the longer degradationtime may be undersized with respect to the dimensions it should have ifit were to be the sole device, so that it does not come into play in thefirst moments of the prosthesis service life.

The other device, made of a material which exhibits a shorterdegradation time, may be sized normally, so that it does comes into playat the very beginning of the service life of the prosthesis.

It may happen that, due to the geometry of the device and/or thelocation at which the device is positioned and/or the characteristics ofthe blood flow, the effectiveness thereof may significantly decreasewell before the complete erosion thereof has occurred.

Therefore, when both the peripheral and the leaflet device are present,that which is expected to lose its effectiveness in a shorter time, ifit were the sole device, may be designed to be eroded in a shorter time.In this way when effectiveness is almost lost (i.e much lowerregurgitation area than that considered when designing the prosthesis),the second device—previously inactive due to its undersizing—may comeinto play and restore the effectiveness.

Additionally, by doing so one may also—so to say—“program” a non linearchange in the regurgitating flow evolution.

With reference to FIGS. 12 to 14, a heart valve prosthesis according tofurther embodiments is shown herein and indicated by the reference 100.

In such embodiments, the heart valve prosthesis 100 is a biologicalprosthetic heart valve including a prosthetic valve annulus 200 and aplurality of biological valve leaflets 400. In the embodiments shownherein the heart valve prosthesis 100 may be suitable for replacement ofaortic or tricuspid valve. With reference to FIGS. 13 and 14, eachleaflet 400 includes a leading edge 402 whereat a coaptation surfacesC100 is provided.

When implanted, the blood flow opens and closes the valve leaflets 400of the prosthesis 100, so that when the leaflets 400 are in the openposition as shown in FIG. 13 the separation between the cooperatingcoaptation surfaces C100 enables the blood flow through the orificedefined by the annulus 200 in the direction F1, and when the leaflets400 are in the closed position shown in FIG. 14 the contact of thecooperating coaptation surfaces C100 prevents the blood flow through theorifice in the direction F2, opposite to F1.

In various embodiments the prosthesis 100 may include a plurality ofdevices 110 located on the coaptation surfaces C100 at a positionproximate to commissures C whereat the valve leaflets re-join. Thedevices 110 are configured for allowing a blood regurgitation throughthe prosthesis 100 by preventing at least in part the contact betweenthe coaptation surfaces C100 (i.e. in correspondence of least a portionof the contact area thereof).

Each device 110 in various embodiments may be in the form of a web, awedge, a tab, a patch, a relief, a shim or a film, made ofbio-degradable/bio-resorbable material, e.g. a gel applied (e.g. coated)on the valve leaflets 400.

When the leaflets 400 are in a closed position, as shown in FIG. 14, thecontact of the coaptation surfaces 100 is prevented at a locationproximate to the commissures C, therefore the regurgitation area isconcentrated primarily at the commissures C.

As in the embodiments previously described, the devices 100 areprogressively eroded by the blood flow impinging thereupon so that theregurgitation area is gradually reduced to zero.

That is, when the prosthesis 100 is used for example in a tricuspidvalve replacement intervention, the preload/afterload of the rightventricle may be initially kept at values corresponding to those of thediseased native heart valve.

During systole, a fraction of the blood intended to be ejected throughthe pulmonary vein leaks through the regurgitating prosthetic valve 100.During diastole, the regurgitated volume is again admitted into theventricle together with the diastolic volume, thereby resembling thebehaviour of the diseased native heart valve. However the behaviour ofthe prosthetic heart valve 100 gradually evolves towards a nominal onei.e. according to the design specifications, which allows for a gradualrecovery of the heart after the valve replacement intervention.

Without prejudice to the underlying principles of the invention, thedetails and the embodiments may vary, even significantly, with respectto what has been described herein, purely by way of non limitingexample, without departing from the scope of the invention as defined bythe annexed claims. Furthermore, various modifications and additions canbe made to the exemplary embodiments discussed without departing fromthe scope of the invention.

For example, the prosthetic valve according to the embodiments of theinvention is not limited to a mitral or a tricuspid valve, as theforegoing disclosure applies to any prosthetic heart valve, regardlessof the type, and the material of the prosthetic heart valve, and alsoregardless of the number and arrangement of the prosthetic valveleaflets.

Additionally, in yet further embodiments of the invention, such as thoseof FIGS. 15-16, other types of devices configured for altering thecoaptation of the valve leaflets are envisaged.

In FIG. 15 a schematic view of a human heart H is provided. The mainblood vessels are labeled for prompt reference (the direction of bloodflow are also shown). Such vessels include the aorta AO, the pulmonaryveins PV, the pulmonary artery PA, the inferior vena cava IVC and thesuperior vena cava SVC. The natural heart valves schematically depictedin FIG. 15 include the pulmonary valve PV, the tricuspid valve TCV, themitral valve MV and the aortic valve AV.

The right atrium and the left atrium are indicated by RA and LArespectively, while the right ventricle and the left ventricle areindicated by RV and LV, respectively.

In FIG. 15 the references associated to the tricuspid valve TCV and themitral valve MV are provided in parenthesis in order to indicate thatthe heart valve prosthesis 100 may replace one of them (at least). Apair of heart valve prostheses 100 are displayed in FIG. 15 just for theease of description, without any limiting meaning.

Instead of the devices 8,10 described in the foregoing, the heart valveprosthesis 100 may be provided with a thread W which is routed so toform a loop at one of the prosthetic valve leaflet 400 (i.e. the latteris pierced by the thread W). After the intervention, the thread may berouted through a papillary muscle, the through the wall of the heart(for example at or near the apex) and then it may be routed through thethorax of the patient in the same way as post-operative electrodes. thethread may then be slightly tensioned in order to produce a smalldeformation of the valve leaflet 400 which in turn prevents at least inpart the contact between cooperating coaptation surfaces C100 of theleaflets 400. The action of the thread W may then cease either by manualremoval thereof or by erosion. In the first case, in various embodimentsno knot is provided on the thread W, so that removal of the thread W mayoccur by simply pulling the wire from outside the body of the patient(additionally, in this way either end may be used to pull the thread).In the second case the thread W shall be made ofbiodegradable/bioresorbable material, so that it will be eroded by theblood flow. Additionally, a subsequent manual removal of the portions ofthe thread W not eroded by blood flow may occur e.g. by pulling the twoends of the thread from outside. However, the manual removal of thethread may turn out to be necessary essentially when anon-biodegradable/non-bioresorbable thread is used, because generally abiodegradable/bioresorbable thread experiences full degradation(therefore completely disappearing) even in the absence of directimpingement by the blood flow.

Furthermore, the inventor also observed that the above method foraltering the coaptation of the leaflets 400 by using the thread W may beperformed on a native, in particular repaired, heart valve.

With reference to FIG. 16, the heart valve prosthesis 100 is shownhaving a device for altering the coaptation of the valve leaflets, inparticular configured for preventing at least in part the contactbetween cooperating coaptation surfaces thereof, according to yetfurther embodiments. In such embodiments the device is a leaflet device1100 in the form of a biodegradable/bioresorbable stitch that creates alocal deformation of one or more valve leaflets 400, in a manner thatresembles at least in part the action of a purse string. The stitch 1100creates a defect in the leafet coaptation by forcing a portion of thevalve leaflet to bulge outwards (for example, in other embodiments itmay be envisaged that the leaflet be bulged inwards), thereby creating asmall regurgitation area RA. After a predetermined amount of time thestitch(es) 1100 is (are) eroded (e.g. resorbed) by the blood flow, sothat the prosthetic heart valve 100 may start to function according todesign specifications, i.e. allowing substantially no bloodregurgitation.

In view of the foregoing it follows that there are envisaged bothembodiments wherein the at least one device configured for altering thecoaptation of the valve leaflets, in particular configured forpreventing at least in part the contact between cooperating coaptationsurfaces thereof, ceases its action by removal thereof (see for exampleFIG. 15), and embodiments wherein such device ceases its action byerosion (see the embodiments wherein the at least one device is made—atleast in part—of biodegradable/bioresorbable material).

The invention claimed is:
 1. A prosthetic heart valve including: aprosthetic valve annulus defining an orifice for the passage of bloodflow, at least one prosthetic valve leaflet member including at leastone coaptation surface configured for cooperating with at least onecorresponding coaptation surface of said prosthetic heart valve toregulate blood flow through said orifice, said at least one prostheticvalve leaflet member being displaceable by the blood flow between aclosed position and an open position to produce, correspondingly, acontact and a separation of cooperating coaptation surfaces, wherein inthe open position the separation of the cooperating coaptation surfacesenables the blood flow through said orifice in a first direction,wherein in the closed position the contact of the cooperating coaptationsurfaces prevents the blood flow through said orifice in a seconddirection (F2), opposite to said first direction (F1), at least onedevice configured for preventing at least in part the contact betweencooperating coaptation surfaces, so that a blood regurgitation in saidsecond direction is enabled, in that said at least one device isconfigured for ceasing its action after a predetermined amount of time,and in that as time passes by the blood regurgitation in said seconddirection is progressively reduced before the device ceases its action,and a ring member defining said prosthetic valve annulus, two leafletsof said at least one prosthetic valve leaflet member movably connectedto said ring member, and said at least one device operatively associatedto each leaflet of said two leaflets.
 2. The heart valve prosthesis ofclaim 1, wherein said at least one device is configured for ceasing itsaction by erosion thereof.
 3. The heart valve prosthesis according toclaim 1, wherein said at least one device includes a peripheral deviceoperatively associated to each leaflet and applied to the ring member,said peripheral device being configured for preventing at least in partthe contact between at least one coaptation surface of the ring memberand a corresponding coaptation surface of the leaflet.
 4. The heartvalve prosthesis according to claim 1, wherein said at least one deviceincludes a leaflet device located at cooperating coaptation surfaces ofeach leaflet, said leaflet device being configured for preventing atleast in part the contact between the cooperating coaptation surfaces ofsaid leaflets.
 5. The heart valve prosthesis according to claim 3,wherein the peripheral device includes a hollow cylindrical sectorcomprising a first portion made of a non-biodegradable ornon-bioresorbable material and a second portion made of a bio-degradableor bio-resorbable material, wherein said first portion is guided into acavity defined by guide walls provided within said ring member.
 6. Theheart valve prosthesis according to claim 5, wherein said peripheraldevice is housed within a wall thickness of said ring member.
 7. Theheart valve prosthesis according to any of claim 5, wherein saidperipheral device is housed in a local enlargement of a wall thicknessof the ring member, said local enlargement protruding radially outwardsfrom said ring member.
 8. The heart valve prosthesis according to claim5, wherein the biodegradable or bioresorbable material is chosen so toexhibit a full degradation in 3 to 6 weeks.
 9. The heart valveprosthesis according to claim 5, wherein the biodegradable orbioresorbable material is chosen among gels which exhibit a fulldegradation in 3 to 6 weeks by surface erosion only.
 10. The heart valveprosthesis according to claim 5, wherein the biodegradable orbioresorbable material is a polymer gel which exhibits full degradationin 3 to 5 weeks by surface erosion.
 11. The heart valve prosthesisaccording to claim 5, wherein when the second portion of the hollowcylindrical sector has a maximum volume, the first portion of the hollowcylindrical sector protrudes outwards of said cavity and radiallyinwards of the orifice of the heart valve prosthesis by a maximumextent, said second portion further extending in a clearance betweensaid first portion and the guide walls.
 12. The heart valve prosthesisaccording to claim 11, wherein the first portion of the hollowcylindrical sector is biased elastically towards the interior of saidcavity.
 13. The heart valve prosthesis according to claim 1, wherein: afirst coaptation surface is provided in correspondence of a straightportion of a “D” shape of said prosthetic valve leaflet member; a secondcoaptation surface is provided at the curved portion of the “D” shape ofsaid prosthetic valve leaflet member, and is configured for cooperatingwith a corresponding coaptation surface of the prosthetic valve annulus,a third coaptation surface and a fourth coaptation surface are providedat parallel rectilinear portions of the “D” shape orthogonal to thestraight portion whereat the first coaptation surface is provided, andare located on opposite sides with respect to the first coaptationsurface; the third coaptation surface and the fourth coaptation surfacebeing configured for cooperating with corresponding coaptation surfaceson the prosthetic valve annulus.
 14. The heart valve prosthesisaccording to claim 1, including two devices, the materials of eachdevice being chosen so to erode over different time spans.
 15. The heartvalve prosthesis according to claim 14, wherein the device made of thematerial with the longer degradation time is undersized with respect tothe dimensions it should have if it were to be the sole device whereasthe device made of a material which exhibits a shorter degradation timeis sized normally.
 16. The heart valve prosthesis according to claim 1,wherein the device is configured so to allow the displacement of theleaflet member between the open position and a position enabling aregurgitation area when the device is active.
 17. The heart valveprosthesis according to claim 16, wherein the regurgitation area isapproximately 25 mm².
 18. The heart valve prosthesis according to claim1, wherein the device is sized and dimensioned so to prevent at least inpart the contact between a pair of cooperating coaptation surfaceswithout contacting directly the coaptation surface on which it is notapplied.
 19. The heart valve prosthesis according to claim 13, whereinthe biodegradable or bioresorbable material is chosen so to exhibit afull degradation in 3 to 6 weeks.
 20. The heart valve prosthesisaccording to claim 13, wherein the biodegradable or bioresorbablematerial is chosen among gels which exhibit a full degradation in 3 to 6weeks by surface erosion only.
 21. The heart valve prosthesis accordingto claim 1, wherein the heart valve prosthesis is a mitral valveprosthesis or a tricuspid valve prosthesis.
 22. The heart valveprosthesis according to claim 1, wherein the leaflet member is soconfigured to provide an action aimed at reproducing that of a nativevalve leaflet.